thanks a bunch for the information.

On Wed, Feb 23, 2011 at 11:52 AM, Jan Wieck <JanWieck at yahoo.com> wrote:

> On 2/23/2011 11:19 AM, Tech Madhu wrote:
>
>> hello all,
>>
>> Iam somewhat new to Slony. Have a question on controlled switchover.
>>
>> I have 1 master/ 1slave setup . When i want to do a switchover, using lock
>> set, move set, how do i know the 'slave' has caught up with the master?
>> Say
>> the slave is behind the master by N transactions, and i issue lock set,
>> move
>> set, will slony automatically ensure the slave gets in sync before doing
>> the
>> switchover? or is it the 'applications' responsibility.. If its the
>> latter,
>> how can i tell when the slave has caught up? I looked at:
>> http://www.slony.info/documentation/monitoring.html
>> I can't easily tell looking at contents of the sl_status, sl_confirm,
>> sl_event if the slave has caught up.. The sl_setsync table shows 0 rows,
>> (sl_setsync : Contains information about the state of synchronization of
>> each replication set, including transaction snapshot data. ). if its 0,
>> does
>> it mean everything in sync?
>>
>
> The MOVE_SET event, generated on the old origin, will cause it to become a
> subscriber. After that, the event is propagated to the new origin, which on
> processing it generates the ACCEPT_SET event, which in turn travels back. So
> if you do
>
> LOCK SET ...
> MOVE SET ...
> WAIT FOR EVENT (ORIGIN = <old_origin>, CONFIRMED = <new_origin>);
> SYNC (ID = <new_origin>);
> WAIT FOR EVENT (ORIGIN = <new_origin>, CONFIRMED = <old_origin>);
>
> you are guaranteed that the switchover is complete and everything is caught
> up.
>
>
> Jan
>
> --
> Anyone who trades liberty for security deserves neither
> liberty nor security. -- Benjamin Franklin
>
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